With the wide application of high strength steel, the technology of blank thermal forming will generally be used in production to solve various problem for its forming. eta/DYNAFORM provides a user friendly interface to perform complicated thermal forming setup.
Thermal forming setup includes five pages: Blank, Tools, Boundary, Contact and Control. Blank and Tools are used to define thermal material for blank and tools. In the thermal forming setup, the user must convert the unit of numerical value for parameters to the corresponding unit on the interface. The program will automatically convert it to standard unit during output.
Blank page is used define the thermal material for blank. If there are multiple blanks, the user may define different material for different blanks. The blank geometry will be defined on the main interface of Blank. If the blank geometry is not defined, it shows No defined blank geometry on the page. The blank material interface is illustrated in Figure 8.2.110.
Figure 8.2.110 Thermal analysis dialog box
MODE
Common thermal material: If there are multiple blanks, use the same material for all of them.
Individual thermal material: If there are multiple blanks, the user may defined different materials for different blanks. Select blank from the list box after this option is selected.
THERMAL MATERIAL
In coupled thermal analysis, besides defining structural material for blank, the user also needs to define thermal materials and one thermal material for tool.
New: Click this button to select a thermal material model from the list. After the material is selected, the Thermal Material dialog box, illustrated in Figure 8.2.112 is displayed.
Figure 8.2.111 Thermal material list
Figure 8.2.112 Thermal material dialog box
EDIT: Edit the defined material parameters.
IMPORT: Allow the user to read in a material from the files with a suffix of “.mat”.
EXPORT: Allow the user to save any defined material in files with an extension of “.mat”.
Similar to Blank, the user can define different thermal materials for different tools. Refer to Section 8.2.8.1.
This function includes Initial temperature, Radiation and Convection of the blank and tool, as illustrated in Figure 8.2.113.
INITIAL TEMPERATURE OF BLANK: set the initial temperature of blank.
INITIAL TEMPERATURE OF TOOLS: set the initial temperature of tools.
RADIATION FACTOR
CURVE MULTIPLIER: Click the button next to it to define a curve. The button label will show the number of points.
HEAT TRANSFER COEF.
Figure 8.2.113 Thermal boundary dialog box
The Contact page includes the definitions for thermal contact parameters and thermal friction. The user may define different contact conditions between different tools and blank, as illustrated in Figure 8.2.114.
THERMAL CONDUCTIVITY: thermal conductivity between gaps.
RADIATION FACTOR
HEAT TRANSFER COEF.
MIN. GAP: If the gap is less than this value, use htc value.
MAX. GAP: If the gap is greater than this value, there is no thermal contact.
ALGORITHM: thermal contact algorithm.
THERMAL BOUNDARY CONDITIONS ARE OFF WHEN PARTS ARE IN CONTACT.
THERMAL FRICTION REQUIRED: Define the curve between dynamic/static friction coefficient and temperature.
Figure 8.2.114 Thermal contact dialog box
The Control page includes some thermal control parameters illustrated in Figure 8.2.115. For thermal analysis or coupled thermal analysis, these parameters can control the solver type, steady-state or transient analysis, linear or non-linear analysis, and time step of thermal analysis, etc.
TIME SCALE FACTOR
STEFAN BOLTZMANN COSTANT(SBC)
THERMAL ANALYSIS TYPE (ATYPE)
0: steady-state analysis
1: transient analysis
THERMAL PROBLEM TYPE (PTYPE)
0: linear problem
1 or 2: non-linear problem which needs to define *CONTROL_THERMAL_NONLINEAR
TIME STEP CONTROL (TS)
0: fixed time step
1: variable time step
TIME INTEGRATION PARAMETER(TIP)
0: set to 0.5. Use Crank-Nicholson scheme
1: fully-implicit.
MAX. MATRIX REFORMATIONS(REFMAX)
Figure 8.2.115 Thermal control parameters dialog box